The above-identified patent application describes a system for measuring the pressure distribution on a load bearing surface such as a seat or bed. The system of the above-identified patent application comprises a two-dimensional array of pressure sensors located within the load bearing surface and a processor for processing the data generated by the pressure sensors. Using the data generated by the pressure sensors it is possible for the processor to evaluate certain attributes of the pressure distribution on the load bearing surface. For example, it is possible to divide the load bearing surface into regions and to determine the fraction of the total load on each region, the mean and median pressure of the various regions, and the pressure gradients between regions.
By testing many different seats with many different human users, it is possible to statistically correlate subjective comfort sensations of the user with certain attributes of the objectively measured pressure distributions exerted on the seats by the users. For example, a seat pan may be divided into eight regions: left thigh, right thigh, left buttock, right buttock, two left bolsters and two right bolsters. Similarly, a seat back may be divided into eight regions: left bolster, right bolster, three lumbar regions and three thoracic regions. It is possible to statistically correlate the fraction of the total load on the seat which is exerted on each of these regions with a user's comfort.
In this manner, it is possible to determine for each seat region a desired range for the fraction of the total load which is exerted on a region. A seat may then be objectively classified as comfortable for a user if the actual distribution of the load exerted by the user on the seat is such that the load fraction in each region falls into the corresponding desired range.
Other attributes of the pressure distribution besides fraction of total load exerted on a region may also be statistically correlated with comfort. For example, small pressure gradients correlate with high comfort levels and large pressure gradients correlate with low comfort levels. One reason for this is that small gradient values indicate that the load is more evenly distributed over a greater surface area of a seat.
It is an object of the present invention to utilize the above-described correlation between certain pressure distribution attributes and comfort to provide an electronic feedback system for automatically reconfiguring a load bearing surface such as a seat or bed to provide a user with a certain desired level of comfort.